Very early in my web career I was introduced to the almost mystical holy grail of web (and now app) properties: increasing user engagement.

The reason is simple. The more time people spend with your property the more stuff you can sell them. The more stuff you can sell the more value you have. Your time is money. So we design for addiction.

Famously Facebook, through the ties that bind, is the engagement leader with U.S. adults spending a stunning average of 42.1 minutes per day on Facebook. Cha-ching.

It turns out this is a very old idea. Casinos are designed to keep you gambling, for example. And though I’d never really thought about it before, I shouldn’t have been surprised to learn retail stores of yore used devices called trade stimulators to keep customers hanging around and spending money.

Never heard of trade stimulators? I hadn’t either until, while watching American Pickers, one of my favorite shows, they talked about this whole category of things people collect that I had no idea even existed!

Here’s an explanation of trade stimulators on the For Amusement Only EM and Bingo Pinball podcast. They are small gambling devices used in stores and bars. Usually it was a mini slot machine or game of chance, like a horse racing game or a dice game. It would vend you a small trinket like a particular color gum ball that could be turned into the shop keeper for a free drink or other prize. The idea is you put money in and you keep spending money at the establishment.

Here’s a beautiful Sun Mfg 2 Wheel Bicycle Trade Stimulator from the late 1800s. The wheels spin and when the wheels stop spinning you add up the numbers by the indicators to learn what prize you've won. It could be a cigar or a drink, for example.